Analog Value Conversion: Function Blocks Fb250 And Fb251 - Siemens SIMATIC S5-100U System Manual

Analog Value Processing
11.6

Analog Value Conversion: Function Blocks FB250 and FB251

11.6.1 Reading in and Scaling an Analog Value
Function block FB250 reads in an analog value from an analog input module and outputs a value XA
in the scale range specified by the user.
Specify the type of analog value representation for the module (channel type) in the KNKT
parameter (see Table 11-17). Define the desired range using the "upper limit" (OGR) and "lower
limit" (UGR) parameters.
Table 11-17. Call and Parameter Assignments of FB250
Parameter Explanation
BG Slot number
KNKT Channel number
Channel type
OGR Upper limit of the output
UGR Lower limit of the output
EINZ Single scan
XA Output value
FB
BU Range violation
UGR
11-22
Type
D KF
D KY
D KF
value
D KF
value
I BI
Q W
Error bit Q BI
Q BI
Scaled range
OGR
Figure 11-11. Scaling Schematic for FB250
- FB250 -
Assignment
0 to 7
KY = x,y
x = 0 to 3
y = 3 to 6
3: Absolute value
representation
(4 to 20 mA)
4: Unipolar represen-
tation
5: Bipolar absolute value
6: Bipolar fixed-point
number
-32767 to +32767
-32767 to +32767
Not relevant
Scaled analog value is "0"
on wirebreak
"1" on wirebreak, illegal
channel or slot number or
illegal channel type
"1" when nominal range is
exceeded
Representation of
the analog input
module
User scaled range
S5-100U
STL
: JU FB 250
NAME : RLG:AI
BG :
KNKT :
OGR :
UGR :
EINZ :
XA :
FB :
BU :
EWA 4NEB 812 6120-02b